Help with short lp

Hi, my luteal phase is only 3-7 days . How do I lengthen it? I have no kids and only possibly has one very early pregnancy. Date of conception was only like one week before but my nipple turned brown and mine have always been beigey pink. Only like one shade of from my actual skin tone and I had bad cravings for pickles ,lemon,sprite and sour kraut. And I didn't know these things could happen so fast but I looked it up and it can. Anyways took pregnancy test and it had two lines but one was really light . So I was gonna wait a few more days and test again. Anyways like the next day I get my period. So I was like I must not be . And my nipples were still brown like a week later so I tested because my period was lighter then normal for me and it was negative. My nipples dis start to lighten but they actually never lightened all the way to the normal shade I had always been. I think that the baby didnt get to implant well enough before my period. I read you need a certain length of a luteal phase for your baby to properly implant in your utueral wall..